Alignment device

ABSTRACT

An alignment device ( 10 ) for indicating alignment between two component parts, the first component part ( 12 ) having an arcuate track ( 14 ) with a track following member in the form of a ball bearing ( 28 ) to follow the track under the influence of gravity to seek an equilibrium position. The body having a signal input ( 18 ) and a signal output port ( 20 ) and the second component part comprising an alignment member axially mounted within the body in restraining engagement with the track following member ( 28 ) so as to be rotationally displaceable within the body in response to displacement of the member  28,  whereby alignment between the alignment member and the input and output ports in response to displacement of the alignment member by the ball bearing, effects operation of an indicator means to provide an indication that such alignment between the alignment member and the alignment ports has been achieved.  
     Further, there is provided a level indicator utilising such an alignment device, together with a power tool utilising such a level indicator to determine when such a tool is held in a horizontal or vertical plane

[0001] The invention relates to an alignment device for indicatingalignment between two component parts and, more particularly, to a levelindicator comprising such an alignment device which is particularlysuitable for use in a power tool.

[0002] It is well known that a pivotally mounted and weighed body willseek an equilibrium position under the influence of gravity. Aparticular and specific digital angle indicator device utilising thisprinciple is disclosed in U.S. Pat. No. 4,253,242 which shows an axiallymounted and weighted disk, rotatably mounted relative to a fixed body.The weighted portion of the disk is responsive to gravity and rotatesrelative to the body. The body comprises an indicator surface used toalign the body to a horizontal plane in such a position the disk willhave aligned itself relative to the body so that apertures in the diskwill allow the transmission of light from a light source to a lightdetector through one of a plurality of holes in the disk, detection ofthe light source indicating the alignment and thus the obtaining of ahorizontal or predetermined angular plane. However, a device of thistype requires very accurate manufacturing techniques and the use ofjewel bearings to allow appropriate and free rotation of the disk withinthe body. In addition, since the rotatable disk utilises a balanceweight in order to be responsive to gravity, such a weight provides amoment on the bearing which can be emphasised to a detrimental affect isany additional and undue force is created such as by dropping thedevice. This undue force could be transmitted directly through the diskto the axial bearings which could damage the bearings and alignment ofthe device. These drawbacks are particularly relevant to use of such adevice in a robust environment.

[0003] This type of alignment device has potential uses in obtainingangle or level measurements. In many activities it is desirable toobtain a level reading, particularly within the construction industry orgeneral DIY activities such as hanging doors or putting up shelves. Theconventional method of obtaining a level is the use of a conventionalspirit level utilising a simplistic arrangement of a straight sealedtube filled with a liquid and having a small bubble or air gap left inthe liquid. The tube is marked with two lines whereby when the tube(usually in a flat mounting board) is laid horizontally the bubblewithin the tube will align between the two lines in the centre of thetube to indicate that the tube and carrier are perfectly horizontal.

[0004] An alternative method of measuring the horizontal is to utilise asimplistic pendulum having a rigid straight bar connecting the pivotpoint with a hanging weight together with a crossbar mounted at 90° tothe vertical bar. The crossbar can be disposed either side of the pivotpoint whereby when the pivot level is hung and the weight achievesequilibrium the crossbar will be positioned in a horizontal plane andthen its ends may be aligned with two notches on a carrier board toalign the board to the horizontal and thus measure the horizontal. Theseare simplistic mechanical devices for measuring the horizontal level.

[0005] However, the drawbacks of conventional levels of this type aretheir sensitivity and unwieldy size making it difficult to use incertain applications. In particular, the use of a power drill requires apreferential alignment of the tool axis horizontally or vertically toallow a hole to be bored in at 90° to an upright material or horizontalmaterial respectively. Obviously, the use of a conventional spirit levelin a drill has significant drawbacks whilst when aligning a drill to thehorizontal it will be effective to indicate when the drill is level (inthe same manner as a conventional spirit level) but once the drill isactivated, the vibrations caused by the power tool will be transmittedto the liquid medium in the spirit level which will then “froth” due tothe vigorous vibrations. Thus, the spirit level is subsequently rendereduseless. Furthermore, a liquid spirit level cannot determine a verticalplane directly. Alternatively, the use of a pendulum type levelindicator of the type described above in a drill is feasible but due toits sensitivity and lack of damping together with the associatedunwieldy size such a product would not be convenient for use in a drill.

[0006] It is therefore an object of the present invention to provide analignment device which is simplistic and cost-effective to manufactureand alleviates the aforementioned problems.

[0007] It is a further object of the present invention to provide alevel indicator incorporating such an alignment device and also toprovide a power tool incorporating such a level indicator.

[0008] According to the present invention there is provided an alignmentdevice for indicating alignment between two component parts, wherein afirst component part comprises a main body having an concave track and atrack following member restrained in engagement with and displaceableabout said track to follow said track under the influence of gravity toseek an equilibrium position; a second component part comprises analignment member pivotally mounted within said body and restrained inengagement with said track following member so as to be directlypivotally displaceable in response to displacement of said trackfollowing member, said device further comprising a first alignment portand a second alignment port in said body and indicator means forproviding an indication when said alignment member is in a predeterminedalignment with both first and second alignment ports.

[0009] According to another aspect of the present invention there isprovided a level indicator comprising this alignment device. Preferablysuch level indicators using this alignment device are used in powertools, particularly power drills.

[0010] There is further provided an invention relating to an electricaltrigger switch for a power tool comprising a trigger having first andsecond elongate switching members longitudinally displaceable against aresilient biasing force into engagement with first and second electricalswitching elements respectively, whereby longitudinal displacement ofsaid trigger moves said first switching member into engagement with saidfirst switching element to effect a first switching operation andcontinued longitudinal displacement of said trigger moves said secondswitching member into engagement with said second switching element toeffect a second independent switching operation.

[0011] Specific embodiments of the present invention will now bedescribed, by way of example only, with reference to the accompanyingillustrative drawings, in which:

[0012]FIG. 1 is a plan elevation of an alignment device;

[0013]FIG. 2 is a cross-sectional view of the alignment device of FIG. 1along the lines II-II;

[0014]FIG. 3 is a perspective view of the internal mechanism of thealignment device as shown in FIG. 1 displaced to a non-alignedconfiguration;

[0015]FIG. 4 is a perspective view of the internal mechanism of thealignment device as shown in FIG. 1 displaced to an alignedconfiguration;

[0016]FIG. 5 is a schematic illustration of the use of the alignmentdevice of FIG. 1 in a conventional builders spirit level used in ahorizontal plane;

[0017]FIG. 6 is a schematic view of the use of the alignment device ofFIG. 1 in a conventional builders spirit level used in a vertical plane;

[0018]FIG. 7a shows a cross-sectional view of an alternative embodimentof a transmitting element of an alternative embodiment of an alignmentdevice;

[0019]FIG. 7b is the input port of an alternative embodiment of analignment device of FIG. 7a;

[0020]FIG. 7c is the output port of an alternative embodiment of analignment device of FIG. 7a;

[0021]FIG. 8 is a schematic view of an alignment device of FIG. 1 usedas a level indicator in a power drill;

[0022]FIGS. 9a and 9 b are perspective views of the inner and outersides of an alternative alignment member for use in an alignment deviceof FIG. 1;

[0023]FIG. 9c is a cross-sectional view showing alignment of thechannels of the alignment member of FIGS. 9a and 9 b;

[0024]FIG. 10 is a schematic view of a modified trigger switch for apower tool; and

[0025]FIG. 11 is a simplified alignment device for use as a levelindicator in a power tool.

[0026] Referring now to FIG. 1, an alignment device (10) consists of amoulded plastics casing or main body (12) formed in two halves (12 a and12 b) which are pressed and held together. The alignment devicecomprises a substantially toroidal track (14) formed by the two halves(12 a and 12 b) having a substantially flat central portion (16). Theflat central portion (16) comprises an air gap extending between the twohalves (12 a, 12 b) of the level indicator providing a directcommunication between any two diametrically opposed points on an innercircumference of said track.

[0027] Located in the outer circumference and on the equator of thealignment device (10) are diametrically opposed alignment ports in theform of a signal input port (18) and a signal output port (20) which, asseen in FIG. 2, provide a communication channel between the interior ofthe alignment device (10) and the outside thereof. As shown in FIG. 1,in hashed lines, and more clearly shown in cross-section in FIG. 2 is analignment member (22) comprising light transmitting element (22) formedsubstantially as a symmetrical cross having four arms (21 a, 21 b, 23 a,23 b), disposed symmetrically about a central pivot point or axis (24),so as to be positioned at right angles to each other effectively formingtwo substantially straight alignment bars either side of the axis (24).This light transmitting element (22) comprises a clear plastics material(such as perspex) although it will be appreciated that any lighttransmitting material may be utilised including a hollow channel throughan opaque body. The element (22) is rotationally mounted within thealignment device (10) by projections (26) mounted on the inwardlydirected faces of the flats (16) (co-axial with the toroidal track axis)so as to engage with corresponding recesses formed coaxial with the axis(24) of the element (22). As such, the element (22) is rotatablyrestrained within the alignment device (10) so as to be freely rotatableabout the central axis of the toroidal track. In this manner, the axisof the toroidal chamber is coincident with the axis of rotation of theelement (22).

[0028] Furthermore, a track following member in the form of a sphericalball bearing (28) is also mounted within the alignment device (10)within the toroidal track (14) so as to be freely displaceable about theentirety of the toroidal track. The ball bearing is shown in hashedlines in FIG. 1 although it will be appreciated that other trackfollowing members could be employed, such as a cylindrical member,provided such members are freely displaceable about the track. Thediameter of the ball bearing is such as to substantially engage twoadjacent arms of the cross element (22) whereby any displacement of theball bearing within the toroidal track in either direction will causethe ball bearing (28) to engage one or other of adjacent arms of theelement (22) to effect direct rotational displacement of the element(22).

[0029] The alignment device (10) also has two additional bolt holes (30)which are to allow the alignment device to be connected to a product inwhich it is to be incorporated for measuring or determining a levelmeasurement, to be discussed later.

[0030] A light source (32), such as an LED or a light bulb, is placedwithin the input port (18) to transmit light through the input port (18)into the toroidal track (14). The output port (20) will have a lightdetector means attached thereto, such means could include a lightsensitive diode or other light detection means but, in the presentembodiment, will comprise a fibre optical cable which will be connectedto a viewing window on the exterior of an article in which the alignmentdevice (10) is mounted. As such, when the light transmitting element(22) is aligned in the manner shown in FIG. 1 so that two opposed arms(21 a, 21 b) are in direct alignment between the diametrically opposedinput (18) and output ports (20) light generated by the light sourceenters through port (18) is transmitted through the light transmittingelement (22) (via arms (21 a, 21 b)) to output port (20) where thenlight is transmitted through the fibre optical cable to the viewingwindow as mentioned above. However, if the light transmitting element(22) is rotationally displaced so that the arms (21 a, 21 b) are out ofalignment with the input and output ports (18, 20) then light enteringthrough the input port (18) is not transmitted to port (20) and thus nolight is received at the port (20) or communicated to the associatedwindow. Hence, light viewed at the window is indicative of alignment ofthe light transmitting means (22) and the associated input/output ports.

[0031] Additionally, it will be appreciated that since there are twosets of opposed arms (21, 23) on the light transmitting element (22),light will be transmitted between the ports when such an element (22) isaligned in one of four configurations so as to provide a lighttransmitting channel between the input (18) and output ports (20).

[0032] Reference is now made to FIG. 3 and FIG. 4, to more clearlydescribe operation of the alignment device (10). Here, the input port(18) has an LED element (34) as a light source. This LED is connected toa battery via a conventional electronic circuit. The output port (20)has a fibre optical cable (36) which is connected to a viewing window(not seen). In FIG. 3, the ball bearing (28) has been displaced aboutthe toroidal track (14) so as to engage with the element (22) todisplace the arms (21 a, 21 b) out of alignment with the input andoutput ports (18, 20) so that light generated by the LED is nottransmitted to the output port. In this manner, when the end user viewsthe window connected to the fibre optical cable no light will be visiblesince the exterior walls of the alignment element (22) will serve toreflect and displace any light away from the output port (20).Alternatively, the element (22) may be formed of a substantially opaquematerial with a light transmitting channel therethrough or employ anopaque coating so as to effectively “block” any light being transmittedthrough the chamber (16) except when alignment is achieved between themember (22) and the two ports. The outer surface of the element (22) andinner surface of the alignment device (10) may additionally be coatedwith light absorbent material to reduce the possibility of reflectedlight, (which does not pass through element (22)), from reaching theoutput port (20).

[0033] Referring now to FIG. 4, here the ball bearing (28) has beendisplaced slightly within the toroidal track so as to displace theelement (22) and effect alignment of the arms (21 a, 21 b) of theelement (22) with the input and output ports (18, 20) respectively. Inthis position light generated by the LED is transmitted through thelight transmitting element (22) to the output port (20) whereby suchlight is then transferred, via fibre optical cable, to the viewingwindow of the article. An end user then looking at the viewing windowwill see the light transmitted and understand that alignment has takenplace.

[0034] In use, the alignment device (10) will be mounted in an articlefor which the detection of a horizontal or vertical level is required.For example, FIGS. 5 and 6 show schematically the use of the alignmentdevice (10) mounted and restrained in a builders level (38) where it isused to replace a conventional bubble spirit level. In use the alignmentdevice (10) is held in a vertical plane (where its axis lies in ahorizontal plane substantially as shown in FIG. 2) and shownschematically in FIGS. 5 and 6. In such a vertical plane, the ballbearing (28) is free to rotate about the toroidal track (14) whereby theaction of gravitational forces ensure that the ball bearing always seeksthe lowest point of the toroidal track. This is clearly illustrated inFIG. 5 and FIG. 6 whereby the ball bearing lies at the bottom of thetrack. Thus, the alignment device (10) is mounted within the article(38) at a predetermined position whereby the track member is fixed fromrotation relative to the article in order that when an indicator (i.e. aflat) surface of the article (38) lies in a substantially horizontalplane, the input port (18) and output port (20) are coincident with thearms (21 a, 21 b) of the element (22) (the position of the element (22)governed by engagement with the bearing (28)) to allow light enteringthe input port (18) to be transmitted through the element (22) to theoutput port (20), as shown in FIG. 5 to provide a visual indication ofalignment between the component ports of the alignment device (10).

[0035] Subsequent rotation or displacement of the level (38) in avertical plane will cause the ball bearing (28) to be displaced (undergravity) within the toroidal track (14) so as to maintain itsequilibrium position at the lowest point of the toroidal track. Once thelevel (38) has been moved out of the horizontal position the subsequentdisplacement of the ball bearing (28) displaces the element (22) out ofalignment between the input and output ports (18, 20). Thus, when thelevel is moved out of a horizontal plane, light generated at the inputport (18) cannot be transmitted to port (20) and thus no light istransmitted to the viewing window (40). However, continued rotationaldisplacement of the level (38) in a vertical plane until, such level ispositioned perpendicular to the horizontal (i.e. vertically) as shown inFIG. 6, will result in the second pair of diametrically opposed arms (23a and 23 b) of the element (22) to subsequently align between the input(18) and output ports (20). Thus, the alignment device (10) will againbe able to transmit light from the input port (18) to the output port(20) through the light transmitting element (22) when it is heldperpendicular to the horizontal (i.e. vertically). Thus the samealignment device (10) is able to detect and indicate when an object (38)is held both horizontally and vertically, as distinct from the currentbubble spirit level which is only able to detect a horizontal position.

[0036] It will be appreciated that the use of a toroidal track memberprovides a track which effectively restrains the bearing (28) inrotational engagement with the outer periphery of said track. Thus nodirect force is transmitted through the member (22) to its axial orpivot point (26). Any axially directed force directed by the bearing(28) is absorbed by a substantially inner surface (37) of the toroidaltrack. However, since the bearing (28) abuts two arms (21 a, 22 b) ofthe member (22) at all times, displacement of the bearing (28) resultsin an effective immediate displacement of the member (22) about theaxis. The significant benefit to be observed here is that should thelevel (38) be accidentally dropped, no force is transmitted from thebearing (28) to the axis (26) of the member (22) to damage therotational ability of such member (22).

[0037] Each of the pairs of arms of the element (22) may contain acharacterising means to affect light transmitted therethrough, such thatthe transmitted light will be indicative of whether the light has beentransmitted through the arms (21 a, 21 b) or arms (23 a, 23 b) andsubsequently indicate whether the alignment device is detecting thehorizontal or vertical. For example, if a white light source is utilisedand the first arm (21 a) of the element (22) comprises a first colouredfilter (or is indeed a translucent coloured light transmitting material)then light transmitted from the input port (18) to the output port (20)will correspond to the colour of the filter material and thus whenviewed through the window (40) will clearly indicate not only thatalignment has been detected but which of the pairs of arms of theelement (22) have been aligned. Where the alignment device (10) is usedin a level (38) one set of arms may produce a first colour indicative ofa horizontal plane being measured and the second pair of arms maycomprise a second colour indicative of the vertical plane beingdetected. Conversely, both sets of arms (21 or 23) of the lighttransmitting element (22) may be of different colours or one may becoloured and the other clear as long as there is a distinction betweenthe colour of the light transmitted through the different arm of suchelement (22). Alternatively, some other form of marking may be placedupon each of the arms (21, 23) of the element (22) which will betransmitted via the fibre optical cable to the viewing window (40) whenalignment is achieved. Such marking could incorporate a lighttransmitting template in the form of a letter such as H for horizontaland V for vertical, which could be mounted on respective end faces ofone or other of the arms (21, 23).

[0038] A further advantage of the design of the alignment device (10) isan inherent damping effect resulting from engagement of the ball bearing(28) with the toroidal track (14). Thus, as the level (38) is displacedfrom a first to second position, displacement of the ball bearing (28)within the toroidal track will set up a oscillating motion which, due tothe engagement between the ball bearing and toroidal track will berapidly damped by the resulting frictional forces. This helps toovercome difficulties encountered with traditional pivotal leveldetection means where damping of such oscillation is difficult toeffect.

[0039] It will be further appreciated that the main body (12) may itselftake the form of a square or rectangle whereby at least onesubstantially flat face of such square or rectangle may be used tomeasure a vertical or horizontal plane. In such an embodiment the inputports and output ports are aligned relative to this measuring face sothat alignment between the member (22) and the input and output ports(18, 20) is achieved when such measuring face is disposed in ahorizontal plane. As best seen in reference to FIG. 1, a hashed line(67) is shown to schematically illustrate where such a measuring planemay be disposed relative to the body (12) and it extends parallel to thestraight line disposed between the diametrically opposed input andoutput ports (18, 20). Alternatively, if an alignment device (10) isrequired to be more compact then it may simply utilise a line or otherindicator means etched on the exterior surface of the body (such as astraight line or a series or two or more points) whereby such anindicator means represents a reference line indicative of a horizontalplane (or vertical plane) when alignment of the device is achieved. Inparticular, the use of a line or series of points on the device itselfmay be useful in aligning the device in a predetermined orientationwithin an article where detection of a horizontal vertical level isrequired.

[0040] Whilst the illustrative example shown in FIGS. 5 and 6 relates toutilising the alignment device (10) in a conventional builders level itis clear that the alignment device (10) can be utilised in a number ofdifferent applications and, in particular, within the field of powertools and notably power drills.

[0041] A desirable feature of the act of drilling a hole in a wall is toensure that such a hole is either horizontal (or if in a ceiling, afloor, vertical) so that the fixing to be inserted in the hole may bereceived flush with the material being drilled. Use of a conventionalbubble spirit level in this manner would create significant difficultiessince, once their tool is operated the inherent and associatedvibrations will cause the liquid to froth with the creation ofinnumerable smaller bubbles making its subsequent function impossible.Therefore, in such a situation the alignment device (10) can be insertedin a drill, FIG. 8, in a manner similar to that described for itsinsertion within a builders level (38) whereby the important featurewhen employed in a drill is that the alignment device (10) is intendedto indicate when the axis of a drill bit held in a drill chuck ishorizontal or vertical. In this respect, it is possible that at leastone half (12 a or 12 b) of the alignment device may be mouldedintegrally with the clamshell of the power tool. In addition, theutilisation of a fibre optical cable (36) allows the level indicator(10) to be positioned anywhere within the drill body wherein the viewingwindow (40) can be positioned at any position of the clamshell desirableor more beneficial to the user to view the transmission of light whenlevel is achieved.

[0042] Alternatively, as now shown in FIG. 8, a power tool such as adrill may utilise an infrared (or ultraviolet) detector (such as aninfrared transistor) to produce infrared radiation instead of visiblelight. Similarly, the detector means disposed at the output port of suchan alignment device (10) consist of an infrared detector such as a pindiode or other form of conventional infrared detector which emits anelectrical signal responsive to detection of infrared radiation. Theelectrical input of such a detector is then processed throughconventional electronic circuit (details of which are not providedherein but may be standard within the art), and which circuit will thenactivate an output signal which can be determined by the end user. Suchan output signal could be visual (e.g. a lightbulb or LED) or audible.

[0043] The current design provides a simplistic and cost-effectivemanner of providing a clearly visible alignment device to indicate whena horizontal or vertical alignment has been achieved. However, it willbe appreciated that this basic inventive concept may be subject to anumber of variations and modifications without affecting the overallscope of the invention.

[0044] In particular, the sensitivity of the alignment device can bevaried, as desired by the manufacturer, by control of the thickness ofthe light transmitting path of the element (22). For example, if theinput port and output port have diameters of 3 mm and the correspondingelement (22) also has a diameter of 3 mm then, provided at least part ofthe outermost face of the arm of the element (22) overlaps at leastpartially with the input and output ports then light will be transmittedbetween the ports. This will allow light to be transmitted between theports over a 3 mm displacement range of the element (22) in eitherdirection about the pivot point. The exact amount of angulardisplacement of the element (22) to effect such 3 mm displacement willof course be dependent on the length of the element (22) and, inparticular, the length from the outer face of the arm and the pivotpoint. The longer such length then the smaller angular displacementrequired to displace the outer face by 3 mm. Thus the sensitivity of thealignment device (10) can be carefully controlled by the dimensions ofthe alignment device (10) and, in particular, the size of the lighttransmitting element (22) and the size of the input and output ports(18, 20). Thus the exact sensitivity of such an alignment device can bevaried dependent on the user requirement.

[0045] If required, the end faces of each of the arms of the element(22) may be covered by a opaque material having a narrow slot or smallhole formed therethrough to correspond with an associated slot throughan opaque material mounted across one or both of the input and outputports (18, 20). This will provide for a higher degree of sensitivitywhereby light would be transmitted only upon substantial exact alignmentof such slots or holes between the ports and element (22) is achieved,with no light being transmitted when the alignment device is evenslightly out of alignment.

[0046] Alternatively, a lower degree of sensitivity may be required andhere light may be desired to be transmitted when the alignment devicemember (22) is within a few degrees either side of exact alignment withthe input and output ports (with reference to use in a level indicator,this would represent a tolerance of several degrees either side of thevertical of horizontal planes being detected). In this situation, lightwill begin to be transmitted when partial alignment between theinput/output ports and the transmitting element (22) is achieved,whereby the intensity of transmitted light will increase to a maximumwhen a perfect alignment is achieved allowing light to be transmittedthrough the whole of the thickness of the light transmitting element.This provides the advantage in an alignment device whereby it is oftendesirable to understand when alignment is being approached (or, in alevel indicator, when the horizontal of vertical planes are beingapproached) so that a fine adjustment can be carried out near thedesired alignment. Here, light intensity will be indicative ofapproaching alignment.

[0047] The above description relates to the basic principle of anembodiment of an alignment device of the present invention, but thereare significant variations and improvements which may be achieved whilstmaintaining the basic inventive concept. In particular, the aboveembodiment describes the use of a light transmitting element (22) totransmit light from an input port to an output port (18 and 20) in orderto recognise when the alignment has been achieved. However, what isimportant with an alignment device of this type is the recognition ofalignment of the light transmitting element with the input and outputports (18 and 20). As previously described element (22) should beregarded as a signal transmitting element for transmitting a signalbetween the input and output port upon alignment therebetween. Thissignal may be optical, electrical or employ other forms ofelectromagnetic radiation such as infrared or ultraviolet radiation(with appropriate detectors). For example, a similar function could beachieved by the use of an electrical conducting element to replace thelight conducting element (22) whereby alignment of such a conductingelement between the input (18) and output ports (20) could be signalledby transmission of an electrical current from an input terminal at theinput port (18) to a corresponding output terminal at the output port(20). This could be effected by replacing the translucent or transparentelements (21 a, 21 b) with insulated conductive elements for engagementwith corresponding carbon brushes or other electrical contact elementsat the input and output ports respectively. Thus, when alignment isachieved, a current will be transmitted through the element (22) fromthe input port to 110 the output port whereby the output current couldthen be used to power a light source or other indicator such as LED orlight bulb to indicate that the level has been achieved.

[0048] In particular, and with reference to FIGS. 7a-7 c, the use ofelectrical contact elements provides for alternative embodiments indisplaying the alignment indication.

[0049]FIG. 7a shows an alternative embodiment of a signal transmittingelement (22′) operated on a similar principle to element (22) as shownin FIGS. 1 through 6 which is again rotationally displaceable about anaxis (24′). In this embodiment the mechanical displacement of theelement (22′) is effected similarly to that as previously described.However, the element (22′) may be made of a non-conductive material,such as plastics, having a series of electrical wires or connections(51, 52) extending therethrough between the diametrically opposed pairsof arms. In this particular embodiment each of the two pairs of arms mayhave wires disposed respectively in two different planes one above theother so that the wires (51) in arms (21′) are lower than the wires (52)extending through arms (23′) as is clearly shown in FIG. 7a. The inputterminals at the input port (18′) are shown in FIG. 7b and comprisethree elongate terminals which are engageable with the both sets ofcontact wires (51 or 52) so that during alignment of either arm (21′ or23′) the respective wires contained in such arms will contact theelectrical elements (53) at the input port (18′). Referring then to theoutput port as shown as FIG. 7c, this will comprise an array of upperand lower contact elements (55 a, 55 b) the upper elements (55 a) toengage with corresponding wires (52) in arm (23′) whereby the lowerelements (55 b) will be contacted by the corresponding using (51) in arm(21′). In such an embodiment the contact elements (55 a) will be inelectrical contact with a series of corresponding LED indicators of afirst colour whereby the lower elements (55 b) will be in electricalcontact with an array of LED indicators of a second colour. Thus,alignment of the first set of arms with the input/output ports will beindicated by a first coloured LED whilst alignment of the second set ofarms will be indicated by a second colour LED.

[0050] It will be further appreciated from the embodiments shown in FIG.7a that each of the arms has a series of three wires for engagement withthree corresponding contact elements on both the input and output ports(53, 55) respectively. This is a further enhancement of the currentinvention to provide additional sensitivity when approaching alignmentbetween the arms and ports. In such a situation as alignment isapproached, the arms (23 or 21′) will be moved into alignment betweenthe input and output ports. As alignment is initiated a first of thewires (51, 52) will effect electrical engagement between one of theinput and one of the output ports to light up one of the associatedLEDs. Further rotation will then effect engagement between two of theinput and output contact elements to light up two LEDs and eventuallywhen perfect alignment is achieved (indicative of measuring a horizontalor vertical plane) complete alignment between the three input and threeoutput electrical connections will be effected through the element (22′)to light up all three associated LEDs. When such an alignment device isused or a level indicator, then dependent on which colour LEDs are litup, the user will be able to determine whether the horizontal orvertical alignment has been achieved. The advantage of this sensitivityis that the user will be notified by one LED when alignment isapproaching whilst the indication of which particular LED is lit up canbe further utilised to indicate which direction further rotation ordisplacement of the alignment device or level (38) is required toapproach full alignment with a horizontal or vertical plane.

[0051] Whilst the preferred embodiments herein have referred to theutilisation of a visible light source to be transmitted from the inputport (18) to the output port (20), such visible light source to be thentransferred via a fibre optical cable to an exterior viewing window, itwill be appreciated that the use of visible light is not an essentialelement to the present invention.

[0052] In particular, the use of a fibre optical cable to transmit thevisible light received at the output port (20) to a viewing window couldbe replaced by the use of a light sensitive diode (pin diode) in theform of a photo-electric sensor. Such light sensors are commonelectronic components and will not be described in any detail here servefor its functional purpose which is to provide an electric output inresponse to receiving a light signal of a predetermined wave lengthwhereby such electrical output is then used to drive an electroniccircuit, which circuit switches on an indicator means and are usually inthe form of a visual light through an LED or lightbulb (although it isenvisaged that instead of a visual output as an indicator of alignment,an audio output could be produced from a loud speaker to provide anaudible signal to the end user that alignment has been achieved). Inaddition, the use of visible light is again not a restriction of thecurrent invention and it is envisaged that ultraviolet or infraredradiation could also be employed to transmit a signal from the inputport to the output port via a signal transmitting member (22) but whereinfrared radiation or ultraviolet radiation is employed then the lightsource at the input port will need to be replaced by an appropriateinfrared emitter or ultraviolet emitter as appropriate and the detectoremployed at the output port will need to be an infrared or ultravioletdetector accordingly.

[0053] Where such light sensitive (including ultraviolet/infraredradiation) detectors are utilised to generate an electrical output thensuch common components utilising pin diodes are also responsive to theintensity of radiation received thereon. In particular, the electroniccircuitry used to amplify the output of such sensor and to switch on anappropriate indicator means, may comprise appropriate means to providean output not only indicative of receipt of the appropriate radiationbut also indicative of the intensity. As previously described, for analignment member or signal transfer member of a large diameter, theintensity of transmitted light will increase as full alignment isapproached. Thus the intensity of radiation received can be analysed byan appropriate circuit to provide an appropriate output signalreflective of the increase in intensity as full alignment is approached.

[0054] The embodiment as shown in FIG. 7a, b and c can be furtheradapted for an optical alignment device (10) similar to that describedwith reference to FIGS. 1 to 6 whereby instead of the element (22)comprising simply a translucent or transparent light transmittingmaterial, the wires utilised in FIG. 7a may be replaced by fibre opticalelements whereby the electrical contacts described with reference toFIG. 7b and FIG. 7c may be replaced by light transmitting and detectingmedium similar to those described with reference to the embodimentdescribed in FIGS. 1 through 6.

[0055] Furthermore, if electrical contact wires or fibre opticalelements are utilised, as described above, then the necessity for theinput and output ports to be diametrically opposed about the centralaxis is no longer necessary since all that is required is alignmentbetween the input and output ports and the signal transmitting elements(22, 22′) and thus curved transmitting elements (21, 23) may be utilisedif so required.

[0056] In its simplest embodiment, the alignment device of the currentinvention simply requires a body having a concave track and a pivotallymounted member which engages with the ball bearing so as to be pivotallydisplaceable in response to displacement of the bearing along the track.The pivotally mounted member requires an alignment member (or signaltransfer member) to extend between a first and second alignment portwhereby alignment between the alignment member and the alignment portsis indicative of a required orientation of the alignment device, and anexternal indication means such as a light source audible warning isrequired to notify when such alignment is achieved. It is not essentialto have a circular or toroidal track but merely a concave track wherebya bearing may find an equilibrium position under the influence ofgravity. It is further not necessary for the alignment member to lieco-axial with an axis of the track, but merely requires that the bearingis maintained in a non load bearing engagement with the alignment memberalong the entire length of the concave track. In the preferredembodiment, this is achieved by use of a circular track and a crosselement, although it will be appreciated that a slideable connectioncould be maintained between the bearing and an arm of the alignmentmember to allow relative displacement of the bearing along a radiallength of the pivotal alignment member.

[0057] In a further modification to the present invention, the crossshaped alignment member (22) may be replaced by a substantially discshaped element (122) as shown in FIGS. 9a through 9 c. The disc shapedelement comprises two substantially identical halves (123) which arepress fitted together to form a single disc (122).

[0058]FIG. 9a shows an inner surface (121) of the disc half (123), eachdisc half having two channels (12&) formed in the surface (121) to bothextend through a central axis (130).

[0059] These two channels extend perpendicular to each other toeffectively quarter the disc. Formed within two of the diametricallyopposed quadrants of each disc, half radially equidistant from the axis(130) is a first substantially circular projection (131) and, oppositethereto a, substantially circular corresponding hole (132). The othertwo opposed quadrants comprise two identical recesses (135) formed inthe periphery of such disc half.

[0060] Referring to FIG. 9b, it is seen that the outer side of each disccomprises a central hub (140) having a cylindrical opening (141) mountedco-axially therewith. In addition, each of the channels (127) formed insuch discs have a projecting channel mounting (150). Each of the twohalves (123) are manufactured in an identical plastics mould, wherebythe two inner faces (121) are then brought into engagement with eachother such that the projection (131) on a first disc half is receivedwithin the hole (132) of the opposed disc half in a co-operating fit torestrain the two halves together as a single disc unit (122). In thismanner, the channels formed on one half of the disc overlie exactly thechannels formed on the other half of the disc (as seen in FIG. 9c) toform a single disc having two channels disposed at 90° to each other.These channels form signal carrying members equivalent to the arms ofthe member (22) previously described, in that they allow transmittal ofa light signal diametrically across the disc. In addition, it will beappreciated that the cut outs (135) of one half of the disc overlieexactly with the cutouts (135) of the other half.

[0061] The mountings (150) for the channels provide the disc (122) withan appropriate width which prevents light from being transmitted acrossthe alignment device in which such a disc is placed. Thus light may beonly transmitted from an input port to an output port of an alignmentdevice through the channels (150) formed between the two discs. In thismanner the disc operates very similar to that of the cross (22), shownin FIG. 1, with the exception here that the ball bearing (28) will bereceived in one of the rebates (135) formed in the periphery of thedisc. Again this serves the function that no axial load is transmittedfrom the ball bearing (28) to the axis (130) of the alignment member.This particular design provides an additional advantage allowing theproduction of relatively small components having transversely extendingchannels therethrough. It will also be appreciated that since the disc(122) is made of two identical halves, it will be perfectly balanced andmoment free about its axis.

[0062] The bearing member (140) provides for axial rotational movementof the disc within the alignment device (10) by receiving appropriateaxial pins from the two halves (12 a and 12 b) of the body.

[0063] Furthermore this particular designs allows a simplifiedmanufacturing process to vary the sensitivity of the alignment device.As seen in FIG. 9c, when the two disc halves are placed together, theresulting channel has an accumulative width for both individualchannels. Thus by varying the dimensions of the channel formed in themould, then the sensitivity of this alignment device can be varied byvarying the cross section of the channel relative to the input/outputport as previously described. In addition, whilst the embodiment shownin 9 a to 9 b relates to a light transmitting channel, it will beappreciated that such channel could be infilled with an electricallyconductive material to provide for transmission of electrical signal ina manner previously discussed.

[0064] It should also be appreciated that whilst a preferred embodimentdescribed herein relates to an alignment device having an input port andan output port diametrically opposed about the axis, this is notessential. The signal to be transmitted may be transferred via a curvedpath, i.e. an electrical current or light transmitted through a fibreoptical cable. Again in its simplest embodiment, the pivot point of thealignment member itself may be considered an input port, e.g. anelectrical contact, whereby the signal transmitting member simplyconnects this input port pivot point to a second part of the alignmentmember, the alignment device only requiring therefore an output port toreceive a signal from the alignment member when alignment is achieved.In this manner, alignment between the alignment member and the inputport is constant i.e. non dependent on the pivotal movement of thealignment member. In such an embodiment, it is only necessary to achievealignment between the alignment member and an output port in order totransmit a signal to the output port in order to generate an externalindication of alignment.

[0065] Furthermore, whilst the embodiments described have utilised aball bearing following a circular path, as determined by thegravitational forces exerted on such a ball bearing, a furtherembodiment of the present invention may utilise a fluid filled alignmentdevice (10) (having input and output ports sealed to retain the fluidwithin the internal cavity of alignment device (10)), whereby the ballbearing is replaced by a lightweight ball, either hollow and air filledor otherwise adapted to have a density less than the liquid containedwithin the alignment device (10). In this manner, a ball held in such aliquid will wish to float to the top of the spherical path of thealignment device (in a similar but opposed manner in which a ballbearing is displaced by means of gravity to the lowest point of thecircular track (14)). However, the principle of using a ball to float tothe highest point of the track (14) so as to displace the element (22)is functionally equivalent to the ball bearing system described withreference to FIGS. 1 through 7 and simply represents an alternativeembodiment, whereby the ball still follows the track under the influenceof gravity to seek an equilibrium position.

[0066] A further alternative will be to replace the ball bearing with aflat circular disc, which will be free to rotate about the track definedby the outer circumference of the alignment device (10) in a mannersimilar to the rotational displacement of the bearing (28).

[0067] In addition, the embodiments above have referred to use of atoroidal track being completely circular to allow movement of thebearing thru 360°. However, the alignment device (10) could be limitedto simply measuring or detecting one alignment position. Here, the trackdefined by the alignment device (10) about which the bearing moves couldbe limited to a quarter circle or less. In such an embodiment, thebearing will encounter a restriction at the extremes of such a quartertrack where it would displace the element (22) out of alignment.However, as alignment is approached the ball would again be displaced bygravity to the lowest point on the track and effect alignment of theelement (22) and ports (18, 20) in the manner previously discussed.

[0068] Finally, the above embodiments have described the use of asubstantially cross-shaped element (22) to be utilised to indicate whenalignment has been achieved indicative of when either the vertical orhorizontal plane has been detected. However, it will be appreciated thatalthough such embodiment requires one of the pairs of arms tocommunicate between the input and output ports to indicate when eitherof the horizontal or vertical have been detected, it is also envisagedthat more than two pairs of arms can be utilised which can be used toindicate, for example, incremental angular settings such as 45° to thehorizontal and vertical, 10° to the horizontal and vertical, etc. Theonly requirement being that the pairs of arms of the element (22) be soorientated as to communicate between the input and output ports when aspecific pre-determined angular alignment is achieved. It will beappreciated that where more than two pairs of arms are utilised in theelement (22) then the diameter of the ball bearing relative to thelength of each of the arms will have to be reduced to maintain freedomof movement of the bearing within the track (14). In addition, thediameter of the track will also have to be increased.

[0069] Where an alignment device (10) of the type described herein isused as a level indicator within a power tool, then such a levelindicator requires a power source. Such power may simply be required toswitch on a light at the signal input port, or it may be required toboth provide the input signal and also to power the electronic circuitryused to convert a signal from a signal detector at the output port togenerate an output indication of alignment. However, a power tool, andparticularly drills, have been ergonomically designed so as to becomfortable for the end user and allow for ease of operation.Furthermore, there has been a significant increase in the use ofcordless power tools utilising battery packs as power sources are afinite source of energy then it is desirable to utilise such energy toits optimum efficiency and certainly not to allow drain of suchbatteries when the power tool is not in use.

[0070] In the present invention the use of alignment device (10) as alevel indicator in a power tool provides a secondary electrical functionrequiring power. The primary function requiring power is obviouslyoperation of the motor to rotate the drill bit. In addition, one of theprimary requirements for the use of a level indicator in a drill is toindicate when a drill bit is level before the operator starts to drillthe hole and then to maintain an indication that the tool is still levelas continued drilling occurs.

[0071] Where two electrical functions have been employed within a powertool historically, such as the use of a light or torch mounted on thedrill, such second electrical functions have required a second switchwhich may be simply toggled from an on to off position and vice versa.This creates an ergonomic problem whereby the switch must be mounted onthe body, usually remote from the handle making it a two handedoperation and, secondly, since the use of the second electrical functionis not dependent on the first electrical function the light has oftenbeen left on and, in the case of a battery powered tool, failing toswitch off the light can drain the batteries and thus reduce optimumefficiency of the power tool. However, in the present invention there isprovided a modified trigger type electrical switch for use in a powertool of the type conventionally used in electric drills.

[0072] Referring now to FIG. 10, there is provided a trigger switch(200) comprising a trigger (210) mounted on a switching box (211), whichswitching box being rigidly mounted to the clamshell of a drill or othertype of power tool (not shown). The trigger switch (210) comprises afirst elongate member (220) extending between the trigger (210) and theswitching box (211), which member is restrained for longitudinaldisplacement into and out of a guide channel (not shown) in the box(211) in a conventional manner. The trigger (210) is resiliently biasedinto an unactuated position shown in FIG. 10 by use of a spring member(218) (which although shown externally here may be mounted internally inthe box 211). In this manner the trigger (210) is held so as to beremote from the box (211).

[0073] In a conventional switch of this type an end user would grip thehandle of a power tool and use a forefinger to “squeeze” the trigger(210) to displace the member (220) into the switching box (211) wherebycompletion of a switching circuit is achieved as the element (220) ismoved into engagement with appropriate switching elements shownschematically as 214. To simplify the understanding of this inventionwithout imposing any undue restriction, we have schematically shown theoperation of the main switching function here by indicating that themember (220) has an electrical contact plate (216) which completes anelectrical contact between two contact elements (217, 219) to completean electrical circuit to allow power from a power source, such as amains power source or a battery power source, to be transmitted to themotor of the power tool, to switch the power tool on. If the triggerswitch (210) is subsequently released by the end user the spring member(18), which has been compressed during activation, then applies itsresilient biasing force to move the trigger away from the switching box(211) to break the electrical contact between the contacts (217, 219).It will be appreciated that this explanation of the operation of thetrigger switch is extremely simplified and it will also be appreciatedthat many conventional trigger switches now used to provide variablepower to a motor, whereby a rheostat may be used to gradually increasepower transfer through the switching box (211) from the battery pack tothe motor to gradually increase motor power and thus output speeddependent on the degree of actuation of the trigger switch. However,such trigger switch configurations are standard.

[0074] The current invention resides in adapting the trigger switch(200) to achieve a secondary switching function to operate the secondelectrical operation of the power tool, and in this particular caseactivation of the level indicator as previously described.

[0075] Referring again to FIG. 10 a second longitudinally extendingelement (232) is further securely attached to the trigger (210) whilst asecond electrical switch (230) is mounted on the external surface of theswitching box (211), and then securely mounted relative to the clamshellof the power tool. The second switching element (230) comprises a simpledepression switch (234) which can be depressed into an actuated positionby pivotal lever (236), which lever (236) abuts an end of thelongitudinal element (232). As shown in the unactuated position in FIG.10 the element (232) abuts but does not affect depression of the lever(236) and thus the switch (234) remains in an unactuated position.However, minimal activation and displacement of the trigger (210) asindicated by the arrow A in FIG. 10 will be sufficient to move theelement (232) a distance sufficient to effect pivotal displacement ofthe member (236) to depress the button (234) and thus activate thesecond switch element (230). The second switch element (230) simplyprovides for an electrical connection between the battery and a levelindicator as previously described.

[0076] It will be further appreciated that movement of the triggerswitch (210) a distance A (corresponding to displacement of the mainmember (220) a distance A′) is insufficient to activate the mainswitching element (211) by failing to complete contact between theelements (214, 219). Further displacement of the trigger switch (210) adistance B, (causing movement of the element (220) distance B′) will besufficient to complete the main switching circuit. However, displacementof the trigger switch (210) a distance B will maintain the element (232)in contact with the pivotal member (236) and thus maintain the switch(230) in an actuated position.

[0077] When the trigger switch (210) is released the member (220) isfirst moved, under the biasing of the spring, out of engagement with theelements (217, 219) to break the main electrical switching circuitbefore the element (232) is moved out of engagement with the secondswitch (230). In this manner operation of the trigger switch (210)firstly actuates the first switching element (230) to provide power tothe level indicator and serves to maintain power to the level indicatoras the power tool itself is subsequently actuated by continueddisplacement of the trigger. Once drilling operation has been completedthe end user will then release the trigger in turn breaking theswitching contact to stop power reaching the motor and only then willthe member (232) move out of engagement with the second switch (230) toswitch off power to the level indicator.

[0078] In this manner an operator of a drill will be able to first alignthe drill to the correct level by operation of the level indicator,subsequently drill the appropriate hole, and then switch off both thepower tool and the level indicator. This prevents the need to operate asecond switch on the power tool whilst automatically ensuring that whenthe tool is not in use and no pressure is being applied to the switchthen no power drain is employed by accidentally leaving the leverindicator switched on.

[0079] It would be appreciated that the description of the triggerswitch typed above is purely by way of example only and simply requiresthe inclusion of the member (232 and 230) to a conventional triggerswitch to provide a second switching operation upon a single actuationof a trigger switch. The exact nature and operation of the conventionaltrigger switch may vary and reflect those trigger switches known in theart.

[0080] It is to be appreciated that the utilisation of this particulartype of switching mechanism in a power tool having a level indicator ofthe type previously described, is equally applicable to a power toolutilising any and all types of electrical level indicators.

[0081] Therefore, the level indicator as previously described may bereplaced by a more simplified embodiment as shown in FIG. 11. The levelindicator as shown in FIG. 11, in exploded form, simply discloses acylindrical housing comprising a top housing (311) and a bottom housing(312) which are mated together (snap fitted) to form a substantiallycylindrical chamber which receives a circular disc (315) which disc(315) has an axially mounted pivot pin (320) extending from either sideof the disc. This pin (320) is received within recesses between the topand bottom housing to axially mount the disk for rotation within thehousing. This disc further comprises a biasing weight (325) which causesthe disc to be displaceable under the action of gravity to seek anequilibrium position.

[0082] The level indicator (300) further comprises a signal generator,in this particular case an infrared transistor (337) and a signalreceiving member (329) in the form of an infrared detector, one eachdisposed either side of the disk within the housing. The disc furthercomprises four pin holes (331) extending therethrough such that apredetermined orientation of the disc relative to the housing (311) willallow infrared radiation to be transmitted through the pin hole to thereceiver to activate an indicator, such as an external light source, ina manner similar to that previously described in relation to thealignment device (10).

[0083] This device provides an output signal indicative of the holes inthe disc (315) aligning with the transmitter/signal receiver devices(337, 329). It provides a similar function to that previously describedand alignment device (10) and it will now be appreciated that indicator(300) may be inserted in a power tool that such alignment is achievedwhen the power tool is disposed in a predetermined horizontal plane(usually determined by the output axis of the motor).

[0084] If the body is rotated relative to the weighted disc to a secondpredetermined distance, a second pin hole may then be disposed betweenthe signal transmitter and receiver and again an indicator provided thata second alignment has been achieved. In this manner, as this type oflevel indicator is placed into a tool such that when the power tool isin a predetermined horizontal or vertical plane. The vertical plane willbe determined 90° relative to the horizontal by placement of the pinholes at 90° relative to one another about the periphery of the disc.Again alignment will be achieved when the axis of the drill motor liesin a horizontal or vertical plane. In this mariner the signal indicator(300) operates similarly to that previously described although thedisplacement of the disc in this embodiment is achieved by directbiasing of such pivotal member. However this embodiment (300) is givenby way of example only as an alternative form of level indicator whichmay take advantage of use of the trigger switch (200) in a power tool.

1. An alignment device for indicating alignment between two componentparts, wherein: a first component part comprises a main body having anconcave track and a track following member restrained in engagement withand displaceable about said track to follow said track under theinfluence of gravity to seek an equilibrium position; a second componentpart comprises an alignment member pivotally mounted within said bodyand restrained in engagement with said track following member so as tobe directly pivotally displaceable in response to displacement of saidtrack following member; said device further comprising a first alignmentport and a second alignment port in said body and indicator means forproviding an indication when said alignment member is in a predeterminedalignment with both first and second alignment ports.
 2. An alignmentdevice as claimed in claim 1, wherein the track is arcuate and disposedabout an axis and said alignment member being mounted and rotatableabout said track axis so as to be displaceable about said axis inresponse to displacement of said track following member.
 3. An alignmentdevice as claimed in claim 2 in which said arcuate track defines acomplete circle about said axis.
 4. An alignment device as claimed inany one of the preceding claims in which the track following membercomprises a sphere.
 5. An alignment device as claimed in any one of thepreceding claims in which said track comprises a channel in which saidtrack follower means is restrained by inner and outer walls of saidchannel.
 6. An alignment device as claimed in any one of the precedingclaims in which said first alignment port comprises a signal input portand said second alignment port comprises a signal output port and saidalignment member comprises a signal carrying member to effect transferof a signal from input port to output port when alignment is achieved.7. An alignment device as claimed in claim 6 further comprisingindicator means which is activated in response to a signal beingtransferred from input port to output port to provide an externaldetectable indication of alignment.
 8. An alignment device as claimed inclaim 7 in which indicator means comprises a light-emitting terminalwhich provides said external indication.
 9. An alignment device asclaimed in claim 7 or claim 8 wherein said input port comprises a signalgenerating means and said output port comprises a signal detector means.10. An alignment device as claimed in claim 9 in which signal generatormeans comprises an electromagnetic radiation emitter and said signaldetector means comprises an electromagnetic radiation detector.
 11. Analignment device as claimed in claim 10 in which the signal-carryingmember comprises an electromagnetic radiation-carrying member.
 12. Analignment device as claimed in any one of claims 9, 10 or 11 whenappended to claim 7 or claim 8 further comprising an electronic controlcircuit which is activated in response to a signal received from thedetector means to provide said 11 external indication of alignment. 13.An alignment device as claimed in any one of the preceding claims inwhich said first and second alignment ports are diametrically opposedabout the axis of the track and said alignment member comprises at leastone substantially straight axially mounted alignment bar which, uponalignment, extends between said ports.
 14. An alignment device asclaimed in claim 13 comprising two alignment bars disposed at rightangles to one another whereby alignment of the alignment means and portsoccurs when either alignment bar extends between said ports.
 15. Analignment device as claimed in claim 13 or claim 14 when appended toclaim 6 in which the or each alignment bar comprise said signaltransmitting member.
 16. An alignment device as claimed in claim 14wherein said track following member is restrained in engagement withboth alignment bars.
 17. An alignment device as claimed in any one ofthe preceding claims in which said alignment member comprises a circulardisc having a restraining notch formed in its circumference forco-operating engagement with said track following member
 18. Analignment member for use in an alignment device according to any one ofthe preceding claims comprising two substantially identical circulardiscs, said member being moment free about an axis extendingperpendicular to and through the centre of the discs when fittedtogether.
 19. An alignment member as claimed in claim 18 in which eachdisc having at least one disc channel formed diametrically across afirst surface whereby engagement between the first surface of each discaligns the at least one disc channel of a first disc with that of theother disc to form a channel through said alignment member.
 20. Analignment member as claimed in claim 19 in which each disc has aprojection and rebate formed from said first surface whereby engagementof the first surfaces of each disc so as to align the disc channels alsoaligns the rebate of one disc with the projection of the other disc toprovide an interference fit between the projection of one disc with therebate of the other disc to restrain the two discs in engagement.
 21. Analignment member as claimed in claim 20 in which said projection andrebate on each disc are equidistant from the centre of each disc.
 22. Analignment member as claimed in anyone of claims 19 to 21 in which eachdisc has first and second identical disc notches diametrically opposedabout the disc whereby alignment of the discs channels of said discsaligns the first disc notch of one disc with the second disc notch ofsaid second disc.
 23. A level indicator comprising an alignment deviceas claimed in any one of claims 1 to 16 wherein alignment between thecomponent parts is indicative of the body substantially identifying ahorizontal plane.
 24. A level indicator as claimed in claim 23comprising a reference surface fixed relative to said body for saidsurface to substantially identify a horizontal plane upon alignmentbetween said component parts.
 25. A level indicator as claimed in claim23 or claim 24 when comprising an alignment device as claimed in claim14 or any one of claims 15 to 17 when appended to claim 14 in whichalignment between said alignment ports and said first alignment bar isindicative of the body identifying a horizontal plane and alignmentbetween said alignment ports and said second alignment bar is indicativeof the body substantially identifying a vertical plane.
 26. A levelindicator as claimed in claim 25 when appended to claim 24 in which saidreference surface substantially identifies a horizontal plane uponalignment between said alignment ports and first alignment bar andsubstantially identifies a vertical plane upon alignment between saidalignment ports and said second alignment bar.
 27. A power drill havinga longitudinally extending rotary output and comprising a levelindicator as claimed in claim 22 or claim 23 in which said body of saidalignment device is fixedly mounted in said drill in a predeterminedorientation so that alignment of said component parts occurs when thelongitudinally extending rotary output lies substantially in ahorizontal plane.
 28. A power drill having a longitudinally extendingrotary output and comprising a level indicator as claimed in claim 25 orclaim 26 in which said body of said alignment device is fixedly mountedin said drill in a predetermined orientation so that alignment betweensaid alignment ports and said first alignment bar occurs when thelongitudinally extending rotary output lies substantially in ahorizontal plane and alignment between said alignment ports and saidsecond alignment bar occurs when the longitudinally extending rotaryoutput lies substantially in a vertical plane.
 29. An electrical triggerswitch for a power tool comprising a trigger having first and secondelongate switching members longitudinally displaceable against aresilient biasing force into engagement with first and second electricalswitching elements respectively, whereby longitudinal displacement ofsaid trigger moves said first switching member into engagement with saidfirst switching element to effect a first switching operation andcontinued longitudinal displacement of said trigger moves said secondswitching member into engagement with said second switching element toeffect a second independent switching operation.
 30. A switch as claimedin claim 29 in which said first switching member is restrained inengagement with said first switching element when said second switchingmember is in engagement with said second switching element.
 31. A powertool comprising an electrical trigger switch as claimed in any one ofclaims 28 to
 30. 32. A power tool as claimed in claim 31 in which bothfirst and second switching operations complete electrical contactbetween the power tool power source and separate electrical functions ofthe tool, wherein the electrical function operated by the firstswitching operation is initiated before the second electrical functionand is subsequently maintained throughout operation of the secondelectrical function. 33 A power tool as claimed in claim 31 or claim 32further comprising an electrically powered level indicator, wherein saidthe first switching operation operates said level indicator and saidsecond switching operation operates the motor of said power tool.
 34. Apower tool as claimed in claim 31 comprising a level indicator asclaimed in any one of claims 23 to 26.